Element 84 - polonium - the first element inscribed in the periodic table after the discovery of radioactivity. It is also the first (in the order of atomic numbers) and the lightest of the elements that do not have stable isotopes. It is also one of the first radioactive elements used in space research.
At the same time, element # 84 is perhaps one of the least known, least popular radioactive elements. At first it remained in the shadows, relegated to the background by the glory of radium. Later it was not advertised too much, like almost all materials of atomic and space research.
Discovery, name
The history of the discovery of element # 84 is well known. It was discovered by Pierre Curie and Maria Sklodowska-Curie. In the Curies laboratory journal, the symbol "Po" (inscribed by Pierre's hand) first appears on July 13, 1898.
A few years after the death of Pierre Curie, his wife and co-author of two of his most striking discoveries wrote the book "Pierre Curie". Thanks to this book, we "first-hand" learn the history of the discovery of polonium and radium, get acquainted with the features and principles of the work of two outstanding scientists. Here is an excerpt from this book: “... The ore we chose was tar blende, uranium ore, which in its pure form is approximately four times more active than uranium oxide ... The method we have applied is a new method of chemical analysis based on radioactivity. It consists in the separation by the usual means of chemical analysis and in the measurement, under appropriate conditions, of the radioactivity of all the products isolated. In this way, you can form an idea of \u200b\u200bthe chemical properties of the desired radioactive element; the latter is concentrated in those fractions, the radioactivity of which becomes more and more as the separation continues. Soon we were able to determine that radioactivity is concentrated mainly in two different chemical fractions, and we came to the conclusion that at least two new radioelements are present in the resin blende: polonium and radium. We reported the existence of the element polonium in July 1898 and radium in December of the same year ... "
The first report of polonium is dated July 18th. It is written with the utmost restraint and correctness. There is a phrase there: "If the existence of this new metal is confirmed, we propose to call it polonium, after the homeland of one of us."
In Latin Polonia - Poland.
“Polonium” is not the first “geographic” name for an element. By that time, germanium, ruthenium, gallium, and scandium had already been discovered. Nevertheless, this name is special, it can be considered as a protest name: an independent Polish state did not exist at that time. Poland was fragmented, divided between the Austrian, German and Russian empires ...
In the famous book "Marie Curies", written by the youngest daughter of the Curies spouses, Eva, the following conclusion was made: “The choice of this name shows that Marie, having become a French physicist, did not renounce her homeland. This is also evidenced by the fact that before the note "On a new radioactive substance in the composition of uraninite" * appeared in the "Reports of the Academy of Sciences", Marie sent the manuscript home, to Joseph Bogussky, the head of that laboratory of the Museum of Industry and Agriculture, where her first scientific experiments began. The message was published in Swialto, a monthly illustrated review, almost simultaneously with the publication in Paris. "
* Mineral of uranium, its composition is UO 2. The Curies studied various uranium-containing minerals.
Why radium and not polonium?
Indeed, why did radium and not polonium bring worldwide fame to the Curies? After all, the first element discovered by them was element # 84.
After a year of work, they had no doubt that two new elements were present in the uranium tar. But these elements made themselves known only by radioactivity, and in order to convince everyone, and above all chemists, that discoveries had really happened, it was necessary to isolate these activities, to obtain new elements at least in the form of individual compounds.
All radioactive elements and isotopes, as you know, are now combined into families: decaying, the nucleus of a radioactive atom turns into an atomic nucleus of another, daughter element. All elements of radioactive families are in a certain equilibrium with each other. It was measured that in uranium ores the equilibrium ratio of uranium to polonium is 1.9 · 10 10, and 0.2 mg of polonium is in equilibrium with a gram of radium. This means that in uranium minerals, radium is almost 20 billion times less than uranium, and polonium is 5 thousand times less.
The Curies, of course, did not know these exact numbers. Nevertheless, realizing what a titanic work to isolate new elements, they accepted the only the right decision... In the book we have already quoted about Pierre Curie, it is said: “The results obtained after a year of work clearly showed that radium is easier to isolate than polonium; therefore, efforts were concentrated on radium. "
Artificial polonium
Here the question is quite pertinent: if polonium is really an ultra-rare and super-difficult to obtain element, then what is the cost of mining polonium in our time?
We do not have exact numbers, but today element no. 84 is no less available than radium. It is really difficult to get it from ore, but there is another way - nuclear fusion.
Today polonium is produced in two ways, with bismuth-209 serving as the feedstock in both cases. In nuclear reactors, it is irradiated with fluxes of neutrons, and then, along a relatively simple chain of nuclear transformations, the most important isotope of element 84 - polonium-210 - is formed today:
And if the same isotope of bismuth is placed in another important nuclear fusion machine, the cyclotron, and fired there with proton fluxes, then according to the reaction
the longest-lived isotope of element 84 is formed.
The first reaction is more important: polonium-210 is a much more interesting isotope for technology than polonium-209. (For reasons - below.) In addition, the second reaction simultaneously with polonium forms lead-209 - one of the most difficult to remove impurities to polonium.
In general, purification of polonium and its isolation from a mixture with other metals is not a particularly difficult task for modern technology. There are various methods of polonium isolation, in particular electrochemical, when metallic polonium is isolated on a platinum or gold cathode, and then separated by sublimation.
Polonium is a low-melting and comparatively low-boiling metal; its melting and boiling points are 254 and 962 ° C, respectively.
Fundamentals of Chemistry
It is quite obvious that the currently existing perfect methods of obtaining and isolating polonium became possible only after a thorough study of this rare radioactive metal... And his connections, of course.
The foundations of the chemistry of polonium were laid by its discoverers. In one of the Curies's laboratory notebooks, there is an entry made in 1898: “After the first treatment of resin blende with sulfuric acid, polonium is not completely precipitated and can be partially recovered by washing with dilute SO 4 H 2 (here and below, the chemical index of the original is preserved). In contrast, two treatments of the resin blende residue and one treatment of the German [ore] residue with carbonates give carbonates, with SO 4 H 2 completely precipitating the active substance from the carbonate dissolved in acetic acid. "
Later, much more was learned about this element. We learned, in particular, that elemental polonium - a silver-white metal - exists in two allotropic modifications. Crystals of one of them - low-temperature - have a cubic lattice, and the other - high-temperature - rhombic.
The phase transition from one form to another occurs at 36 ° C, but at room temperature, polonium is in a high-temperature form. It is heated by its own radioactive radiation.
By appearance polonium is like any common metal. By fusibility - for lead and bismuth. Electrochemical properties - for noble metals. According to the optical and X-ray spectra - only on himself. And according to the behavior in solutions - to all other radioactive elements: thanks to ionizing radiation in solutions containing polonium, ozone and hydrogen peroxide are constantly formed and decomposed.
In terms of chemical properties, polonium is a direct analogue of sulfur, selenium and tellurium. It exhibits valencies 2–, 2+, 4+ and 6+, which is natural for an element of this group. Numerous polonium compounds are known and sufficiently well studied, ranging from the simple oxide PoO 2, soluble in water, to complex complex compounds.
The latter shouldn't be surprising. The tendency to complexation is the lot of most heavy metals, and polonium is one of them. By the way, its density - 9.4 g / cm 3 - is slightly less than that of lead.
A study of the properties of polonium, very important for radiochemistry as a whole, was carried out in 1925 ... 1928. in Leningrad Radium Institute... It was fundamentally important to find out whether radioactive elements found in solutions in vanishingly small quantities can form their own colloidal compounds. The answer to this question - the answer is positive - was given in the work "On the question of the colloidal properties of polonium." Its author was I.E. An old man, later a famous radiochemist, corresponding member of the USSR Academy of Sciences.
Polonium on Earth and in Space
To people far from radiochemistry and nuclear physics, the following statement will seem strange: today polonium is much more important elementthan radium. The historical merits of the latter are undeniable, but this is the past. Polonium is an element of today and tomorrow. First of all, this applies to the isotope polonium-210.
A total of 27 isotopes of polonium with mass numbers from 192 to 218 are known. This is one of the most multi-isotopic, so to speak, elements. The half-life of the longest-lived isotope, polonium-209, is 103 years. Therefore, naturally, in earth crust there is only radiogenic polonium, and there is extremely little of it - 2 · 10 –14%. Several isotopes of polonium that exist in nature have their own names and symbols that determine the place of these isotopes in the radioactive series. So, polonium-210 is also called radium F (RaF), 211 Po - AcC " , 212 Po - ThC " , 214 Po - PaC " , 215 Po - AcA, 216 Po - ThA, and 218 Po - RaA.
Each of these names has its own history; all of them are associated with the "parent" isotopes of one or another atomic variety of polonium, so it would be more correct to call them not "names" but "patronymics". With the advent modern system isotope designations the listed old names gradually almost fell out of use.
The most important isotope of polonium-210 is a pure alpha emitter. The particles emitted by it are decelerated in the metal and, running only a few micrometers in it, waste their energy. Nuclear energy, by the way. But energy does not appear and does not disappear. The energy of the alpha particles of polonium is converted into heat, which can be used, say, for heating and which is not very difficult to convert into electricity.
This energy is already being used both on Earth and in space. The 210 Po isotope is used in the power plants of some artificial satellites. In particular, he flew outside the Earth to soviet satellites "Cosmos-84" and "Cosmos-90".
Pure alpha emitters, and polonium-210 in the first place, have several obvious advantages over other radiation sources. First, the alpha particle is massive enough and therefore carries a lot of energy. Secondly, such emitters practically do not require special protection measures: the penetrating power and path length of alpha particles are minimal. There are third, and fourth, and fifth, but these two advantages are the main ones.
Basically to work on space stations Plutonium-238, Dolonium-210, Strontium-90, Cerium-144 and Curium-244 are acceptable as energy sources. But polonium-210 has an important advantage over other competing isotopes - the highest power density, 1210 W / cm 3. It generates so much heat energy that it can melt the sample. To prevent this from happening, polonium is placed in a lead matrix. The resulting alloy of polonium and lead has a melting point of about 600 ° C - much higher than either of the constituent metals. The power, however, decreases, but it remains quite large - about 150 W / cm 3.
W. Corliss and D. Harvey, authors of the book "Energy Sources on Radioactive Isotopes" (in Russian this book was published in 1967), write: "As shown latest research210 Po can be used in manned spaceships". As another advantage of polonium-210, they mention the availability of this isotope. The same book says that bismuth and polonium obtained from it are easily separated by ion exchange. So the polonium space service is apparently just beginning.
A good start has been made. The radioactive isotope polonium-210 served as the fuel for the "stove" installed on the "Lunokhod-2".
The nights on the moon are very long and cold. For 14.5 Earth days, the Lunokhod was at temperatures below –130 ° C. But all this time, the instrument container had to maintain a temperature acceptable for sophisticated scientific equipment.
The polonium heat source was placed outside the instrument container. Polonium radiated heat continuously; but only when the temperature in the instrument compartment fell below the required limit, the coolant gas heated by polonium began to flow into the container. The rest of the time, the excess heat was dissipated into space.
The Lunokhod-2 nuclear stove was distinguished by complete autonomy and absolute reliability.
However, polonium-210 has a limitation. Its relatively short half-life - only 138 days - puts a natural limit on the life of radioisotope sources with polonium.
Similar devices are used on Earth. Besides them, polonium-beryllium and polonium-boron sources of neutrons are important. These are sealed metal ampoules, which contain a ceramic pellet made of boron carbide or beryllium carbide coated with polonium-210. A flux of neutrons from the nucleus of a boron or beryllium atom generates alpha particles emitted by polonium.
Such neutron sources are lightweight and portable, completely safe in operation, and very reliable. A brass ampoule with a diameter of 2 cm and a height of 4 cm - a Soviet polonium-beryllium neutron source - gives up to 90 million neutrons every second.
Among other earthly affairs of element # 84, its use in standard electrode alloys should probably be mentioned. These alloys are needed for glow plugs in internal combustion engines. The alpha particles emitted by polonium-210 reduce the voltage required to generate a spark, and therefore make it easier to start the engine.
Safety engineering
Special care must be taken when working with polonium. Perhaps this is one of the most dangerous radioelements. Its activity is so great that, although it emits only alpha particles, you cannot take it with your hands, the result will be radiation damage to the skin and, possibly, the whole body: polonium quite easily penetrates inside through the skin. Element 84 is also dangerous at a distance exceeding the path of alpha particles. It is able to quickly transform into an aerosol state and contaminate the air. Therefore, they work with polonium only in sealed boxes, and the fact that it is not difficult to protect oneself from the radiation of polonium is extremely favorable for everyone who deals with this element.
The attentive reader has probably already noticed that in this article wherever it is said about the practical use of polonium, only one isotope appears - with a mass number of 210. Indeed, other isotopes of element No. 84, including the longest-lived polonium-209, are still did not go outside the laboratories.
True, many scientists believe that polonium-208, also a pure alpha emitter, is also promising for space energy sources. Its half-life is significantly longer than that of polonium-210 - 2.9 years. But so far this isotope is almost unavailable. The future will show how long it takes to walk only in promising ones.
Polonium (lat. Polonium), Po, a radioactive chemical element of the VI group of the periodic system of Mendeleev, atomic number 84. Polonium is the first element discovered by its radioactive properties by P. Curie and M. Sklodowska-Curie in 1898. Named in honor of Poland (lat. Polonia) - the homeland of M. Sklodowska-Curie. There are 25 known radioactive isotopes of Polonium with mass numbers from 194 to 218. The most long-lived is the artificially obtained α-radioactive 209 Po (half-life T ½ \u003d 103 years). There are 7 polonium isotopes in nature with mass numbers of 210-212, 214-216 and 218 as members of the radioactive series of uranium, actinouranium and thorium. The most stable of them is the α-radioactive 210 Ро (Т ½ \u003d 138 days). Milligram quantities of 210 Po can be isolated not only from natural objects, but also synthesized artificially by the nuclear reaction of neutrons with bismuth. Almost all information about Polonia was obtained using 210 Ro.
Polonium is a rare element; its content in the earth's crust is about 2 · 10 -15%. Free Polonium is a soft, silvery-white metal; density 9.3 g / cm 3, melting point 254 ° C, boiling point 1162 ° C. The configuration of the outer electron shell of the atom is 6s 2 6p 4. In terms of chemical properties, Polonium is closest to tellurium. In compounds (like Te) it exhibits oxidation states -2, +2, +4 and +6. Known oxides PoO, PoO 2 and PoO 3. Under the action of Zn on a hydrochloric acid solution of Polonium, volatile hydride PoH 2 is formed. Polonium solutions contain PoO 4 2-PoO 3 2-, Po 4+ and Po 2+ ions.
Known polonium hydroxide - PoO (OH) 2.
The readily hydrolyzable Polonium tetrahalides and sulfates of various compositions were synthesized in weight amounts. By the method of carriers (using the analogue of Polonium - tellurium), organopolonium compounds were synthesized in which the Po - carbon bond occurs [obtained, for example, diphenyl Polonium (C 6 H 5) 2 Po, diphenyl Polonium dichloride (C 6 H 3) 2 PoCl 2, etc. etc.]. Polonium is extremely toxic and therefore work with it is carried out in special boxes.
The 210 Po isotope is used in neutron sources. The energy of 210 Po alpha particles can be converted into electrical energy. Electric "atomic" batteries with 210 Ro, which have a long service life, were used, in particular, on the Kosmos-84 and Kosmos-89 satellites.
Polonium-210 (210 Po) is a common component of natural radioactive fallout. It enters plants from the soil through the roots or from the atmosphere as a result of deposition on aboveground organs. In small quantities (10 -4 pc / g) 210 Rho is in sea \u200b\u200bwater; can accumulate in marine organisms (in seaweed Porphyra umbilicalis, its accumulation coefficient is ~ 1000). In the organism of animals and humans, 210 Ro enters with food. The approximate content of 210 Ro in sea fish is 20-100 pc / kg, meat - 2-3 pc / kg, bread - 1 pc / kg, groats - 2 pc / kg, tea - 500-600 pc / kg. In animals and humans (specific concentration of about 4-10 -5 pcuries / g of wet tissue), polonium is relatively evenly distributed over individual organs. The biological effect of 210 Po is due to α-radiation. Experiments on animals have shown the high toxicity of this radionuclide in high concentrations. Thus, concentrations of 210 Po above 0.0003 μcurie / g of live weight reduced the life span of white rats, changed the composition of peripheral blood, and caused liver cirrhosis; In the long term, the animals developed tumors of the kidneys, large intestine, testes and a number of other organs. The biological effect of low concentrations of 210 Rо has not been sufficiently studied.
In London, Litvinenko's murder brought the topic of the use of polonium for poisoning back to the front pages of the media. We talk about this chemical element with the Doctor of Chemical Sciences, Head of the Laboratory of the Radioisotope Complex of the Institute for Nuclear Research of the Russian Academy of Sciences Boris Zhuikov... Interviewed Natalia Demina.
In 2006-2007, you have repeatedly made comments about polonium poisoning on Echo of Moscow, NTV and other Russian and foreign media. After all, many at first did not understand what had happened. It was argued that this substance was illogical to use, and in general, the very fact of polonium poisoning was questioned?
Yes, there was such a point of view. For example, Lev Fedorov, Doctor of Chemistry, President of the Union for Chemical Safety, said on the air of Echo of Moscow: “How can you poison with polonium-210? This I will not put my mind to .... Now, if I were thinking how to poison a person, then the last one I would call polonium ... Naturally, the person who would drag it across the borders, he had to drag it in a lead container ".
A participant in the discussion that took place in the television program "Sunday Evening with Vladimir Solovyov" on December 3, 2006, in which I participated, Maxim Shingarkin, an artilleryman by training, argued that Litvinenko was not poisoned, but he himself breathed polonium while working in a secret laboratory on the territory Great Britain. ( later M. Shingarkin became an advisor to the chairman of the Federation Council Committee on Science and Education, a consultant to the Commission under the President of the Russian Federation for the modernization and technical development of the Russian economy, and now he is a deputy State Duma, an associate of Andrei Lugovoi in the LDPR faction - "Polit.ru").
It's hard to understand: the people who said this - they simply do not understand this area at all or are engaged. Already in my first commentary on this topic, I said that polonium-210 is a fairly suitable substance for poisoning, and the most likely method of poisoning is oral administration: throw a capsule with a soluble shell in tea or coffee, because it is sufficiently absorbed through the stomach ... And literally the next day, they reported that they found a kettle contaminated with polonium, from which Litvinenko drank tea. Can you imagine my position? ( Laughs).
Have you had any experience with polonium in your practice?
Yes, many years ago, when I worked as a researcher at the Joint Institute for Nuclear Research in Dubna, I dealt with polonium-210 and other isotopes of polonium, in trace amounts. In general, I have worked with radioactive isotopes of almost all elements. This was the direction - we were looking for new, undiscovered elements in a complex mixture of products of various nuclear reactions and in natural samples. Now I deal most of all with radioactive isotopes for nuclear medicine, isotopes that are introduced into the human body for the diagnosis and treatment of various diseases.
Do you know people who are now related to polonium?
Yes, but by the nature of their service they are unlikely to agree to give you a frank interview, they have their own rules.
Well it is clear. After all, what relates to polonium is probably secret?
No, the very properties of polonium, its behavior, production methods and application have long been no secret, everything has been published. There are also a number of publications on the effects of polonium on animals. The specialist can understand and correctly interpret what is relevant to a given case.
How expensive is polonium to manufacture?
Talk about the high cost of polonium-210 is a myth. I know the price it sells for, but I probably shouldn't divulge it. In any case, it is very small. Of course, manufacturers of a specific drug - a source of radioactive radiation, convenient for use, can ask for a decent amount, but this, as they say, is a "cheat". Polonium itself is cheap. Also, the source used, although obviously made by professionals, is badly done, made by bad professionals.
Where can you make such a conclusion?
Polonium, by its properties, diffuses easily through organic shells and generally spreads easily. In such cases, the source is made with a multilayer coating. The people who made the sample either did not know this, or were too lazy, or hoped that the presence of polonium would not come up at all. So the performers inherited decently.
If polonium is so inconvenient to use, why was it used?
On the contrary, in principle, polonium-210 is a very convenient substance for poisoning, precisely for latent poisoning, and not for provocation. Initially, it is very difficult to detect if you do not do special analyzes (alpha spectrometry). And no one was going to do special analyzes, since this substance had not been used for poisoning earlier - at least it was not found. Polonium-210 differs from other radioactive isotopes in that it emits almost exclusively alpha particles with an energy of 5.3 MeV, which are absorbed even by a sheet of paper. On the other hand, gamma radiation, which is usually detected using Geiger counters, is extremely weak, only one hundred thousandth part. Accordingly, it is not a problem to bring it to England, lead containers are not needed for such quantities, and it is safe to perform various operations with a sufficiently sealed capsule.
Opinions were heard that polonium was used for provocation. In my opinion, such conversations are absolute nonsense. There was no provocation, there was a secret murder attempt. For provocation, it would be advisable to use any other radionuclide, for example, americium-241 - it would be easier to detect, it is more accessible (it is used everywhere in smoke detectors).
How, then, was this polonium discovered?
Yes, they did, they might not. it interesting story, I followed the developments on the Internet. Litvinenko's symptoms were consistent with radiation damage. However, nothing was found with an ordinary counter that registers gamma radiation. The very weak 803 keV gamma-ray line could be seen only as a result of long-term measurements using a good gamma spectrometer. At first, this radiation was mistakenly attributed to radioactive thallium (thallium-206), which is produced by the decay of alpha-active bismuth-210m.
But then this version was recognized as erroneous, since this isotope of bismuth has too long a half-life, and they began to consider the possibility of the presence of other alpha emitters. After that, the urine was analyzed for the presence of alpha-active radionuclides and polonium was found, moreover, in huge quantities. The assumption that the British scientists were “prompted” about polonium-210 by some provocateurs seems to me extremely unlikely. Everything was done consistently and logically enough.
Why didn't they use the usual chemical poison?
All groups of chemical poisons are known and would be easier to detect. Even when “disappearing” poisons are used, some traces of their use remain.
Was polonium unknown?
Unknown as poison. Of course, there have been very few cases of industrial poisoning. But in production, after all, they are poisoned by anything.
But now ...
Now you don't have to worry and don't carry the alpha counter with you. Nobody will use polonium anymore for this purpose. I am sure about that. The story became too popular, and even I was pulled with a request to check something ... It's another matter - old cases that happened even before the poisoning of Litvinenko, for example, the mysterious death of Yuri Shchekochikhin, an attempt to poison Anna Politkovskaya ...
But so many years have passed, is there really anything left? After all, the half-life of polonium-210 is 138 days?
Yes, this means that in 10 years its number decreases 100 million times. Polonium-210 will remain, but in very small quantities. It is estimated that at least 1-3 billion becquerels (decays per second) were injected into Litvinenko a second time. This is a very high activity, even too high activity: as a result, a person can die in a few days. But the polonium-210 produced in the reactor must contain a small admixture of another, long-lived isotope - polonium-209 (half-life 102 years).
At first, it is very difficult to detect it due to the background of the 210th. But after the collapse - then you should try. It is possible, of course, to make polonium-210 without admixture of 209, but this will be really very expensive and difficult. It is unlikely that these people who made the drug would be engaged in such things. Although, who knows?
There were opinions that Yasser Arafat was poisoned with polonium. What did the research show?
A detailed study by Swiss scientists (the report has been published) showed that there is no good reason to talk about poisoning in this case, although the authors themselves first drew a different conclusion from their results. The report provides fairly convincing evidence that some excess polonium (which really was) was most likely of natural origin - obviously the result of the decay of radon-222, which is abundant in the undergrounds where Arafat often stayed. An autopsy revealed a corresponding amount of another radon decay product - lead-210. And no polonium-209 was found. Thus, Arafat received many orders of magnitude lower dose of polonium-210 than Litvinenko, and this could not be the cause of death.
At public hearings, information was heard that Litvinenko was killed the second or third time. Apparently, the killers wanted to be on the safe side?
Yes, this fact has long been known and published in scientific literature. It has been reliably established by the distribution of polonium in Litvinenko's body. Moreover, the first dose administered was much less. Litvinenko would have died later anyway, and then, probably, nothing at all would have been discovered. But apparently the customers were impatient ...
Tell me, if as a result of such detailed studies it was possible to determine the nature of the introduction of polonium into Litvinenko, then perhaps it would be possible to determine the role of A. Lugovoi and D. Kovtun, suspected by the British?
Of course of course. They were studied, as far as I know, at the Medical Biophysical Center named after A.I. Burnazyan. It was reported that polonium was found in Lugovoi, but detailed results that would help shed light on the man's role are unknown. And they did not go to the UK.
Was there a danger of injury to the performers and injury to those around them? The British media reported that Lugovoi even brought his son to the last meeting and gave him to shake hands with Litvinenko ...
There was some danger, given that the performers were apparently not properly instructed. But still, it is not at all as dangerous as taking polonium orally, and does not pose a danger to life. Lugovoi himself said that someone had dirty him. And whether he got dirty or he did something himself - this could be seen. And the fact that they followed him and deliberately left traces is just stupidity, it is unrealistic to organize so that it is not revealed.
In your opinion, everything that the lawyer of the Litvinenko family said, and the British investigating authorities, is it true?
At least as far as the behavior of polonium is concerned, there is no contradiction. It is only wrong that its use has created a great threat to others. Small amounts of polonium that can contaminate people in contact with Mr Litvinenko can be found, but they are practically harmless to health. As a result, according to the Health Protection Agency, only 52 people received an increased dose, but not enough to significantly increase their risk of illness in the future. The real danger would be if only someone finished their tea for Litvinenko. It is also wrong that polonium-210 is very expensive, unless it is ultra-high purity. I have already mentioned this above. It is simply not readily available, and its distribution is fairly well controlled by government agencies.
Do you see any inconsistencies in what the British investigators say?
There are no discrepancies that cannot be explained based on the physical and chemical properties of polonium. On the contrary, as soon as opponents begin to put forward some objections, these objections do not fit with scientific data at all.
Thanks for the interview.
History of radioactive chemical element Polonium-210 begins in 1898, when it was discovered by the Curies in one of the uranium resin ores. The element was named after Poland, the homeland of the discoverers (Latin Polonium). It was Irene Curie, according to one version, who became the first victim of the element, as she once admitted that a test tube with polonium broke in her laboratory. She died of cancer a decade later.
Examples of polonium-210 poisoning in history
Various versions of frequent cases of cancer began to come later from many parts of the world from research centers and institutes.
Also, at first there were all kinds of rumors about the involvement of the substance polonium-210 in the death of Palestinian leader Yasser Arafat, since traces of this element were found among the personal belongings of the victim... But, despite the initiation of a criminal case, the causes of death were not fully clarified, and all the guesses that the assassination attempt was committed by the Israeli special services remained speculations. However, in 2012, the body was exhumed and the collected material was handed over for research and a verdict by independent experts from different countries. The three laboratories include institutions in France, Switzerland and Russia. A year later, the first results of the research were ready, which came from the Swiss Lausanne and were handed over to the Palestinian capital for review. The results of research by scientists from other countries were also transferred to the Palestinian city of Ramallah.
The results of the examinations were received directly by the widow of Yasser Arafat, from whom all external world and received information that confirmed an early version that the leader was indeed poisoned with polonium-210.
Polonium-210 poisoning also occurred in former officer FSB Alexander Litvinenko as a result of an alleged attempt on his life by his former employees and colleagues in London. This became one of the most striking and resonant cases of an international scandal, and the investigation of the case is still ongoing, for more than 10 years. He died a painful death in a London hospital after 22 two days of severe suffering, when at first his leukocytes almost disappeared, then his bone marrow began to contract, and then his liver, kidneys and heart alternately failed.
The Litvinenko case
As the investigation showed, on November 1, 2016, in the foyer of the London fashionable Millennium hotel, Alexander Litvinenko met with former colleagues Andrei Lugovoy and Dmitry Kovtun, where poison was added to the tea. As a result of the lethal tea poisoning, Litvinenko felt unwell in the evening and began vomiting frequently. On November 4, Litvinenko was hospitalized at the district hospital, and on November 17 at the University College Hospital (UCH). On November 20, he was transferred to intensive care.
This case was taken over by the anti-terrorist division of Scotland Yard, which investigated the causes of the poisoning, and actions were taken to detect the poisonous substance. In addition to a wide variety of analyzes, a gamma-spectrum radiation detector was used, which detects the content of most toxic substances if they are contained in biosamples, but nothing was found. Then the samples of biomaterials were transferred to the Research Institute of Atomic Energy, where they were engaged in the development and creation of nuclear warheads. Polonium content was discovered by scientists completely by accident - the described behavior of the isotope was discussed out loud between specialists, and they were heard by a developer related to a nuclear reactor, who immediately recognized the behavior of polonium, since polonium-210 is part of atomic weapons.
On the day the cause of the poisoning was discovered, November 23, Litvinenko died. An investigation by the special services found traces of the rare isotope in places visited by the alleged killers - Andrei Lugovoy and Dmitry Kovtun - on the plane, at the stadium, in cafes, hotels, restaurants and cafes.
Polonium-210 has been discovered:
- on the plane on which Lugovoy flew to Moscow after the incident;
- in the house of A. Litvinenko;
- at Heathrow airport;
- at the hospital on Easton Road;
- at the office of the security company on Gronover Street;
- at Millennium Hotels, Sheraton Park Lane;
- at its sushi bar;
- in the office of B. Berezovsky.
The day after her husband's death, the widow Maria Litvinenko was forced to leave her apartment - she was given only 20 minutes to get ready. According to investigators, such measures were necessary for her safety - the apartment was seriously contaminated with radiation. On December 1, the widow will still be hospitalized with a high concentration of polonium-210 in her body.
Panic over a possible mass contamination with polonium-210 swept the entire city, and analyzes were taken from visitors to the sushi bar and other places where investigators found a radioactive trail.
But for unknown reasons, the British government refused to issue forensic reports, autopsy results and other documents of the investigation to the Russian side. Russia, in turn, concluded that England was interested in distorting the facts, which would make it possible to adjust all events to the version they were developing.
The Russian Federation conducted an investigation and ruled that D. Kovtun and A. Lugovoi were also victims, an attempted murder was recognized and traces of polonium-210 poisoning were found. In the case of Litvinenko's murder, a criminal case has been opened, under suspicion of which, in addition to the British government, is seen A. Litvinenko's companion from Italy Mario Scaramella, with whom a meeting took place at the Itsu sushi bar a few hours before the meeting at Millennium. Litvinenko himself, already in the hospital, said that he felt bad just after meeting with his Italian colleague. In Itsu, he handed him documents on the case of Anna Politkovskaya. Traces of polonium-210 were also found at Scaramella, in his hotel room and at other addresses of his presence.
After the incident, more than a thousand victims called the hotline of the London service, more than a hundred were found to contain polonium-210.
What is polonium-210 used for?
Radioactive polonium is a relatively soft, silvery-white metal found in uranium ore. Unique in many respects, this element was the first to be included in the periodic table as radioactive. Located at number 84, it differs in that it is the lightest element among the non-stable isotopes. Used in space exploration.
It was not known to the general public until it became the cause of scandalous deaths. It is very rare in nature, in order to obtain it artificially, a nuclear reactor is needed. The list of countries that are engaged in the production of polonium-210 is very wide - it includes North Korea, and Israel, and a number of other countries, including Russia.
The half-life of polonium-210 is 138 days and 9 hours, then it loses its radioactive properties. It quickly oxidizes in the air, it cannot be handled and breathed near. Due to alpha radiation at long distances, it is not dangerous and the harm is significantly reduced if the distance of the dangerous object exceeds 10 cm.
Used when removing static electricityas a heat source in space objects, for industrial purposes as a neutron source, as an experimental method for fighting cancer.
Polonium-210 has also been found in tobacco leaves, confirming the harmful health benefits of smoking. However, it has not yet been possible to remove the isotope from tobacco leaves.
Polonium-210 poisoning symptoms and treatment
The production and manufacture of polonium in Russia and in other countries is strictly classified by the government and every milligram of mined metal is controlled. For this reason it's quite difficult to meet polonium somewhere by chance, although, for example, in the USA, there have been attempts to use it in household utensils - for example, in the form of an antistatic brush, to which dust does not stick. Safe packaging neutralizes the radioactive harm of the element, and the property of alpha particles in polonium acts as intended - in this case, it ionizes the air.
But if, nevertheless, there was contact with a deadly poison, which is polonium-210, you should immediately seek medical help.
Having no obvious signs, such poisoning provokes the development of radiation sickness with pronounced symptoms of radioactive damage. The resulting harm and symptoms directly depend on the dose of the element.
Like poisoning with other highly toxic metals, polonium-210 poisoning is manifested by the following symptoms:
- nausea, vomiting, diarrhea;
- tachycardia, coupled with hypertension;
- fatigue, loss of strength;
- violation of consciousness, delusional states;
In addition to general symptoms, radiation sickness has a number of pronounced features that are externally manifested in hair loss, general sharp aging of the body and further failure of all organs, starting with the liver, as the first fighter for the processing of the drug, and the kidneys, as a tool for its elimination. In the future, at a critical dose, there is a complete defeat of the immune system and the leukocyte formula, which is responsible for it. Hence, there may be additional signs of a lack of lymph and bone marrow.
Once in the body, polonium-210 is evenly distributed through the blood to all organs and tissues. Its almost uniform concentration can be noticed within a few hours after poisoning. The metabolic processes of organs after contact with the poison are disturbed in the same way as the systems - circulatory, nervous, digestive, cardiac. The stool eventually becomes bloody, or its complete absence is possible. CNS disorders can cause seizures, psychosis and delusions. The peripheral nervous system no longer provides motor motility, which leads to its impairment, as well as to terrible weakness. Violation of cardiac activity provokes attacks, the autonomic system - tachycardia and pressure. The person can also become partially or completely blind.
Treatment should be started as early as possible, since the longer polonium remains in the body, the more chances it is to pass the "point of no return" and fatally harm organs. Polonium is very well absorbed into all organs and tissues, so infection is possible if you just touch the metal. Once inside, this isotope is absorbed into organ tissue in just a few minutes. When touched, immediately and abundantly rinse the area of \u200b\u200bthe body that has been in contact with the isotope, laundry soap or washing powder.
If polonium enters the body through the esophagus, induce vomiting immediately. Since the count goes on for minutes and you cannot wait, doctors use apomorphine in the form of injections under the skin. Next, you need a laxative - magnesium sulfate, sodium sulfate, enemas.
Polonium can be completely eliminated from the body by the kidneys within 6-11 months, but during this time it can accumulate and cause harm - for example, partial or complete baldness.
If the polonium is absorbed deep enough into the tissue of organs, then doctors use compounds based on drugs such as unitiol and oxathiol, which are able to "get" polonium-210 "from the depths" and bring it out. They are administered using a dropper in a hospital for a week. After such treatment, recovery occurs.
Since polonium-210 is quite difficult to detect, and also due to the rarity of such poisoning, the issue has not been fully studied, which reduces the chances of a favorable prognosis. Therefore, in the treatment of such poisoning, the main step is to diagnose the disease as early as possible, so that there is time to help the body before the deadly poison has damaged the organs too much.
Scientific aspects of the Litvinenko case for TrV-Science were analyzed by Dr. chem. sciences, head. laboratory of the radioisotope complex of the Institute for Nuclear Research RAS
The passions around the mysterious death of Alexander Litvinenko continue unabated. Finally, public hearings on his case began in London. And more recently, interest in this topic has been fueled by the assumption that Palestinian leader Yasser Arafat was killed in a similar way. Thanks to this, the general public learned at least something about radioactive isotopes and their possible use, however, very one-sided.
At one time I had to comment on this matter in many Russian and foreign publications, radio and television programs. But the mass media is not the most suitable platform for discussing the scientific aspects of this interesting problem: the issue is too politicized. People put forward the most fantastic versions, not bothering themselves with any evidence at all. At the same time, there are a number of scientific publications in which various, primarily medical, aspects are discussed. This question was also raised at a number of scientific conferences on the production and use of isotopes, in which I took part.
Here I will briefly outline the following aspect: the production and properties of polonium-210, which may be associated with the poisoning of A. Litvinenko. A number of Russian “experts” expressed surprise at why this particular substance was used, and many did not understand how it was used. In particular, Lev Fedorov, doct. chem. Sci., President of the Union for Chemical Safety, said on the air of Echo of Moscow: “How can you poison with polonium-210? Now, I won't put my mind to this ... Now, if I were thinking how to poison a person, then the last in a row I would call polonium ... Naturally, the person who would drag it across the borders, he had to drag in a lead container ".
A number of other experts tried to substantiate their conclusions based on general considerations. For example, the famous banker Alexander Lebedev, himself a former KGB employee, stated in our public discussion with him on the NTV channel ("Sunday evening with Vladimir Solovyov", December 3, 2006): "I assure you that there is no way today to allow our special services to engage in such things, there is not even the slightest ... Because this will necessarily be followed by criminal punishment."
Let's put aside the political aspects, who was profitable or not. Let's see why they used polonium?
Obtaining polonium-210
The main method for producing polonium-210 is irradiation of bismuth with slow neutrons in a nuclear reactor (see Fig. 1). Then it is necessary to chemically isolate polonium from the irradiated bismuth. This can be done by sublimation (since polonium has a relatively high volatility at elevated temperatures), electrochemical or other methods. Polonium-210 produced in this way is very cheap. Talk about its high cost is not true. Its availability is another matter.
There is also a third stage in the technology, this is the preparation of the radiation source for the final application. Sources can be of different types. In this particular case, the polonium should be placed in a capsule, preferably with a multilayer shell (to avoid polonium penetration). For poisoning, it is necessary either to open this capsule so that the contents get into the drink, or, which is much more convenient, to make a miniature ampoule with a dissolving shell, it is not difficult.
For the first time, polonium in its pure form in the Soviet Union was obtained at NII-9 (now the High-Tech Research Institute inorganic materials named after A.A. Bochvar), who was a leader in the study of this element. The work was carried out under the guidance of our outstanding scientist Zinaida Vasilievna Ershova.
Is it possible to determine the origin of polonium technically? This is theoretically possible, but in practice it is very difficult. Each nuclear reactor (in a certain irradiation channel) is characterized by its own neutron spectrum. The presence of fast neutrons leads to the formation, along with polonium-210 (half-life - 138.4 days), small amounts of polonium-209 (half-life - 102 years, alpha-particle energy - 4.9 MeV) by the nuclear reaction (n, 2n) from the accumulated polonium-210, as well as even smaller amounts of polonium-208 (2.9 years).
Thus, in principle, it is possible to determine the place and date of production of polonium from such a "nuclear clock". However, this is not easy, and in certain cases even impossible. It depends on how much polonium was found and where it was found: the important is the ratio between the stable lead-206 formed from polonium-210 and the background lead, the content of which in the natural mixture of isotopes is 24.1%. A special mass separator for the separation of polonium isotopes (or a long exposure for the decay of polonium-210) will be required, as well as calibration samples of polonium from the reactor, prepared in the same irradiation mode.
Russian polonium is produced at the All-Russian Research Institute of Experimental Physics in Sarov. Irradiation of bismuth at the reactor is carried out, apparently, in another place - P / O "Mayak" in Ozersk Chelyabinsk region... The method of obtaining polonium-210 is not secret, therefore it can be produced at any other reactors where there is a special channel for irradiating targets in order to obtain isotopes. Such reactors are found in several countries around the world. Power reactors are generally not suitable for this, although some of them have a channel for irradiating targets. More than 95% of polonium-210 was reported to be produced in Russia.
There are also other methods for obtaining polonium, but they are now practically not used, since they are much less productive and more expensive. One of these methods, used by Marie Curie, is the chemical separation from uranium ores (polonium-210 is contained in the decay chain of uranium-238). Actually, polonium was discovered in 1898. Also, polonium-210 can be obtained at charged particle accelerators for nuclear reactions 208 Pb (A, 2n) or 209 Bi (d, n). Moreover, not every accelerator is suitable for producing polonium-210. This requires an alpha particle or deuteron accelerator. There are not so many such accelerators in the world. They are in Russia and Great Britain. However, as far as I know, in Britain the Amersham accelerator is not tuned to alpha particles for a long time and is constantly working exclusively for the production of medical isotopes for diagnostics. In a number of places abroad that I have visited, colleagues have told me that their facilities have been inspected to see if they have produced polonium.
At one time JSC "Techsnabexport" sold polonium-210 to Great Britain (to Reviss). But that was five years before the sad events, and, as my colleagues told me, the firm was very carefully checked after that. Products containing polonium are not officially shipped to the UK from the USA and Russia. Polonium-210 was previously obtained at the Oak Ridge National Laboratory (USA), but now it is not produced in significant quantities there, but, on the contrary, a certain amount is obtained from Russia.
The operation of both reactors and accelerators is strictly controlled. If someone decides to produce polonium illegally, with the existing control system it can be easily revealed.
Nuclear physical properties
As mentioned, the half-life of polonium is 138.4 days. This means that every 138 days its activity decreases by 2 times, and in two years - about 40 times. This half-life is very convenient for using a radionuclide as a poison.
When polonium-210 decays, it emits alpha particles with an energy of 5.3 MeV, which have a small range in solids... For example, aluminum foil tens of microns thick completely absorbs such alpha particles. The gamma radiation that could be detected by Geiger counters is extremely weak: gamma quanta with an energy of 803 keV are emitted with a yield of only 0.001% per decay. Polonium-210 has the lowest gamma constant of all common alpha-active radionuclides. For example, americium-241 (widely used, for example, in smoke detectors) has a gamma constant of 0.12, and for Po it is 5 · 10 -5 P × cm 2 / h × mCi (where P is roentgen, mCi is millicurie ). At the same time, the dose coefficient and, consequently, the radiotoxicity are quite comparable.
Thus, even without a protective shell, it is extremely difficult to detect a sufficient amount of polonium-210 for poisoning with a conventional counter, since the radiation level is comparable to the natural background (see Fig. 2). Thus, polonium-210 is very convenient for covert transportation, and there is no need even to use lead containers. However, during transport, special care must be taken to avoid depressurizing the container (see below).
Polonium-210 is not at all advisable to use for provocations, since it can be detected only with the help of special equipment, which is not used in ordinary cases.
The 803 keV gamma line can only be detected by long-term measurements using a good gamma spectrometer, and the semiconductor detector must be located very close to the source. There is evidence that this is exactly how the increased radioactivity in Litvinenko was initially found, but at first the radiation was mistakenly attributed to radioactive thallium (thallium-206), which is obtained during the decay of bismuth-210m (see diagram in Fig. 1).
This was reported on the Internet even before polonium was identified. But then this version was recognized as erroneous, since this isotope of bismuth has too long a half-life, and they began to consider the possibility of the presence of other alpha emitters. After that, the urine was analyzed for the presence of alpha-active radionuclides and polonium was found, moreover, in huge quantities. The assumption that the British experts were "prompted" about polonium-210 by some provocateurs, it seems to me taken from the ceiling. British scientists did everything consistently and quite logically.
On the surface, the alpha activity of polonium-210 can be detected using an alpha counter, which is usually used only for special purposes, and not for routine checks for radioactive contamination. However, in order to determine that the radiation refers specifically to polonium-210, more sophisticated equipment, usually stationary, is required - an alpha spectrometer. Activity on the order of 1 Bq (decay per second) at the surface can be easily detected. If alpha activity is detected, then sample preparation is already performed (for example, using chemical isolation) and a line in the alpha spectrum of 5.3 MeV is detected on an alpha spectrometer, which characterizes this particular alpha-active radionuclide.
Chemical properties
Polonium can exist in different chemical forms, but in this case it is most likely to be found in the form of soluble compounds (for example, nitrates, chlorides, sulfates), while in a significant part in solution it can also be in colloidal form. It is important that polonium from neutral and weakly acidic solutions is largely sorbed on various surfaces, in particular, on metal and glass (the maximum sorption is at pH ~ 5). It is difficult to completely wash it off using conventional methods. Therefore, it is not at all surprising that a teapot and a cup were discovered, from which polonium was consumed.
Polonium itself in trace amounts begins to sublimate only at temperatures of about 300 ° C. But he can go into environment also together with the water vapor in which it is contained, and in the process with the recoil nuclei.
Polonium diffuses easily enough in plastics and other organic substances; sources based on it are made with a multilayer coating. And if the ampoule was depressurized, then with the help of an alpha counter, even the smallest traces of it can be detected.
Polonium is a polyvalent element prone to the formation of various complexes and can form various chemical forms. In this regard, some of it spreads quite easily in the natural environment. Therefore, it is quite understandable that traces of polonium have spread, and from them it is possible to trace the source of polonium contamination.
Biological impact and radiation safety
Biological studies of the effects of polonium on animals were carried out in our country mainly in the 60s at the Institute of Biophysics in the laboratory of Professor Yu. I. Moskalev, there are several publications.
It has long been known that polonium-210 is one of the most dangerous radionuclides. The levels of human damage with polonium-210 are given in the table (data from experiments with animals were recalculated by us for the weight of a person).
The assimilation of this substance through the gastrointestinal tract is estimated from 5 to 20%. Through the lungs, it is more effective, but such an introduction is extremely inconvenient for latent poisoning, since it can greatly contaminate others and performers. Only about 2% per day is absorbed through the skin, and this use of polonium for poisoning is also ineffective.
Polonium is distributed throughout the body to all organs, but, of course, not quite evenly. And it is excreted from the body with any biological substances: feces, urine, then ... The half-life, according to various sources, is from 50 to 100 days. One industrial accident in our country was reported that resulted in the death of a person 13 days after being hit by 530 MBq (14 mCi) of polonium.
According to indirect data (on the impact), the amount of polonium introduced into Litvinenko could be (0.2-4) × 10 9 Bq (becquerels), that is, decays per second, by mass it is 1-25 μg, an almost invisible amount ...
If polonium was contained in a cup of tea, for example, ~ 10 9 Bq per 100 g, then up to 0.01–0.10 ml, that is, up to 10 5 –10 6, could accidentally fall on people sitting next to them as drops or aerosols. Bq. This does not pose a serious danger to human life, although it exceeds the permissible pollution standards. Such an amount can be easily detected, and an activity of the order of 1 Bq is also detected.
The following happened in the Litvinenko story, according to the Health Protection Agency:
- 120 people may have been exposed to polonium, but received a dose below 6 mSv (millisieverts), which does not pose any health risk;
- 17 people received a dose higher than 6 mSv, but not so significant as to cause any disease in the near future; the increase in the risk of disease in the distant future is probably very small. The highest dose, nevertheless not life-threatening, was naturally received by the wife of Alexander Litvinenko, Marina, with whom he was in contact the most.
The permissible dose for professionals working with radioactivity in Russia is 20 mSv / year. The annual doses received by humans from natural background radiation are 1–10 mSv / year, and in some places on Earth it is much higher, and the mortality rate is not increased there. Only irradiation with an effective dose over 200 mSv during the year is considered as potentially dangerous. Thus, it is an exaggeration to claim that the use of polonium has created a great threat to others.
The press raised the question whether polonium-210 had been used as a toxic substance before and whether it could be established. In particular, the poisons with which Y. Shchekochikhin were probably poisoned and who tried to poison A. Politkovskaya remained unknown. If polonium-210 was present in these cases, then over the past time it has decayed to a level below the background level. However, upon exhumation, polonium-209 may be detected, which could have been present as an impurity (see above).
The hypothesis of the poisoning of Yasser Arafat with polonium-210 was practically not confirmed. Some excess of polonium-210 can be explained by natural causes - inhalation of radon-222 during the long stay of the Palestinian leader in the bunker. Polonium-210 is a decay product of radon. Corresponding amount of lead-210 was found in Arafat's body, which is also a decay product of radon.
Application
Until now, polonium-210 has been used for the following purposes.
1. To create autonomous energy sources generated as a result of alpha decay. The Soviet Lunokhod and some satellites of the Kosmos series were equipped with such devices.
2. As a source of neutrons, in particular, for initiators of a nuclear explosion in atomic bombs... Neutrons are formed when beryllium is irradiated with alpha particles and initiate a nuclear explosion when the mass of uranium-235 or plutonium-239 becomes critical. Also, such sources were used for neutron activation analysis of natural samples and materials.
3. As a source of alpha particles in the form of applicators for the treatment of certain skin diseases. Now it is practically not used for such purposes, since there are much more suitable radionuclides.
4. As an air ionizer in antistatic devices such as the Staticmaster manufactured by Calumet in the USA. These materials are not exported to the UK, and many of these devices would have to be recycled to extract the polonium-210 needed for poisoning, which requires a radiochemical laboratory.
Conclusions related to Litvinenko's death
Conclusions of a technical nature that may turn out to be significant for solving a crime can be divided into two groups: quite definite and those that are highly probable, but an unambiguous statement requires an investigation not only in the UK, but also in Russia.
Quite definite
1. Polonium-210 is a poisonous substance for hidden use. Its main difference from other radioactive substances is the difficulty of initial detection. Accordingly, it makes no sense to use it for provocation, there are much more accessible and suitable radionuclides.
2. Polonium-210 - a substance that is conveniently secretly transported in quantities sufficient for poisoning. It is also easy to covertly introduce it into a person's drinking. Other methods of administration (for example, aerial spraying or through the skin) are less effective, unreliable, difficult, and very dangerous to the poisoner.
3. Accidental contamination with polonium-210 by negligence is practically unbelievable, since this degree of contamination requires a huge amount that can exist only in places of mass production of polonium in a plant, and this can be easily determined by the distribution of polonium on the human body.
4. None of the released statements of the UK investigative authorities contain technical contradictions.
Highly likely, but require confirmation
1. Polonium-210 is most likely produced in Russia. It could have been brought to the UK from Russia or the USA, where this substance is officially supplied. Other sources are in principle not excluded, but it would be practically impossible to hide such production. Polonium-210 has not been produced in the UK for a long time.
2. Removal from antistatic devices in the US requires a dedicated radiochemical laboratory, which is extremely difficult to hide under the US control system. In other countries, such antistatic devices are practically not used.
3. It is possible to establish the origin of polonium by analysis only under certain circumstances (sufficient quantities and concentration, absence of background lead, sufficient exposure before analysis, availability of a special mass separator and samples for comparison). Under favorable conditions, it is also possible to establish in which production cycle it was obtained.
4. Substance has not been stolen. This is extremely difficult to organize under the existing control system. Earlier, several facts of the disappearance of polonium were recorded, but they were all disclosed, since it is not a big problem to reveal them.